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CIRCUIT DESCRIPTION
1. When the food is placed in the oven cavity and door is closed.
• The contact of the interlock monitor switch open (NO).
• The contacts of the primary interlock switch and secondary interlock switch close.
15A Fuse
12A Fuse
TM
2. When the timer is set to the time desired.
• The contact of the timer switch close.
• Oven lamp turn on.
• 230V AC is applied to the high voltage transformer.
• Turntable motor start rotating and glass tray rotating.
• Fan motor rotating and cools the magnetron by blowing air.
• Timer motor operating and point to passing cooking time.
• 3.3 Volts AC is generated from the filamente winding of the high voltage transformer. This filament voltage is
applied to the magnetron to heat the magnetron filament through two noise preventing choke coils.
• A high voltage of 2000 Volts AC is generated in the secondary of high voltae transformer and this secondary
voltage is increased by the action of the diode and the charging of the high voltage capacitor. This resultant
D.C voltage is then applied to the anode of the magnetron. As shown in Fig. 2 the first half cycle of the high
voltage produces in the high voltage transformer secondary charges the high voltage capacitor. Current flow is
in the direction of the dotted-line during the second half cycle, the voltage produced by the transformer
secondary, and the charge of the high voltage capacitor are combined and applied to the magnetron as shown
by the solid line so that oscillations begins.
The disturbance wave generated by the magnetron is prevented by the choke coils of 1.5µH, filter capacitors of
500pF and the magnetron's shielded case so that TV and radio programs are not impired by noise.
Timer Motor
CL
Cavity Lamp
Primary
Timer
Interlock
Switch
Switch
NO
COM
NC
Interlock
Monitor
Switch
Secondary
Interlock
Switch
GM
Geared Motor
Fig. 1
12
TM
CL
GM
FM
FM
Fan Motor
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